This invention relates to a method of supporting the establishment of a telephone call from a calling terminal through an IP network to a telephone terminal of a telephone network, to a server for supporting the establishment of telephone calls between calling terminals and called terminals through an IP network, and to a computer product for supporting the establishment of telephone calls between calling terminals and called terminals through an IP network.
The invention starts from the establishment of telephone calls through IP networks as is described, for example, in ITU-T Specification H.323, 2/1998, pages 1 to 2 and pages 12 to 34.
An H.323 gateway provides an interface between an IP network (IP=Internet Protocol) and a telephone network. The gateway encodes, compresses, and packetizes voice and/or video signals from the telephone network and then transports them as IP packets to a terminal of the IP network or to another H.323 gateway. In the reverse direction, the gateway decodes, decompresses, and disassembles the IP packets coming from a terminal of the IP network or from another H.323 gateway, so that the voice and/or video signals can be routed through the telephone network to a terminal of this network. This makes it possible to establish a telephone connection over which the voice and/or video signals are transported through an IP network.
To control the routing within the IP network, the VOIP gateways may contact a gatekeeper. The gatekeeper makes a central address translation function available to the VOIP gateways.
The object of the invention is to speed up the establishment of a telephone call that can be routed in part through an IP network.
This object is attained by a method of supporting the establishment of a telephone call from a calling terminal through an IP network to a telephone terminal of a telephone network, the method comprising the step of contacting a server of the IP network for routing the call through the IP network, wherein if the server of the IP network determines that the call is directed to a telephone terminal of a telephone network, it contacts a server of this telephone network, that the server of the IP network requests from the server of the telephone network number portability information about the telephone terminal to which the call is directed, and that based on the requested number portability information, the server of the IP network determines from a set of VOIP gateways available between the IP network and the telephone network that VOIP gateway through which the call is to be routed into the telephone network, and initiates the routing of the call through this VOIP gateway into the telephone network.
The object of the invention is further achieved by a server for implementing the above method, the server comprising an interface unit for communication with components of the IP network, and further comprising a control unit designed to control the routing of a specific call through the IP network when contacted for this purpose by one of the components of the IP network.
The object of the invention is still further achieved by a computer product for supporting the establishment of telephone calls between calling terminals and called terminals through an IP network according to the above method, the computer product being designed to provide, in conjunction with a computer, a control unit which controls the routing of a specific call through the IP network when contacted for this purpose by a component of the IP network.
The idea underlying the invention is to contact a server of a telephone network for routing a VOIP call (VOIP=Voice over IP) through an IP network if the VOIP call is to be routed to a telephone terminal of the telephone network through the IP network. The information, particularly number portability information, that is provided by the server of the telephone network about the routing of the VOIP call within the telephone network is then used to control the routing within the IP network.
One advantage of the invention is that the establishment and routing of VOIP calls is optimized and speeded up.
Furthermore, the invention permits a VOIP call to be established to the called terminal as directly as possible. The path used for establishing the call in the telephone network is minimized. Routing of the call to the called terminal through networks of two or more telephone network operators is avoided. All these advantages also result in advantages both for the caller in terms of the charge to be paid for a VOIP call and for the VOIP service provider in terms of revenue collected.
Advantageous developments of the invention are set forth in the subclaims.
It is particularly advantageous that for a VOIP call, both called telephone terminals of the telephone network and called IP terminals within the IP network are addressed by a telephone number, and that number portability is provided between number ranges assigned to the IP terminals of the IP network and number ranges assigned to telephone terminals of the telephone network.